The subject matter disclosed herein relates generally to signaling in obscured environments, and more particularly to a signaling device that may be used by first responders in a smoke filled building.
First responders, such as firefighters, are often relied upon to extinguish fires in buildings or other structures. Additionally, the firefighters are relied upon to rescue persons within the buildings. However, fires typically generate smoke that reduces the visibility within the building and therefore also may reduce the ability of the firefighters to navigate within the building to either extinguish the fire and/or to rescue persons trapped within the building.
Accordingly, thermal imaging cameras are gaining widespread use, particularly by the firefighting community for use within buildings that are experiencing reduced visibility caused by, for example, smoke. In operation, thermal imaging cameras enable the firefighters to operate in various environments wherein the firefighter's vision may be obscured because of the smoke and/or other materials entrained in the air. Thermal imaging cameras operate in the infrared light spectrum and therefore provide an alternative view to firefighters by enabling the firefighters to “see” in the reduced visibility environment. More specifically, temperature differences between various objects in the building are highlighted and transformed into a visible image on a display that forms part of the thermal imaging camera. The visible images enable the firefighters to navigate throughout the building. The visible images also enable the firefighters to locate a prone or injured person within the building. Thermal imaging cameras further enable a firefighter to locate a “hot spot” that may be obscured by walls or furniture so that an extinguishing agent may be utilized to eliminate the hot spot.
However, thermal imaging cameras do not enable the firefighter to identify rooms within the building that have been previously entered by firefighters to rescue persons or to extinguish fires. Thus, traditional methods are used to mark or identify areas where a firefighter has already entered or searched. For example, one traditional method of marking a previously searched room or area includes positioning a chock outside the room. Another traditional method of marking a previously searched room includes etching a tool mark on the door of the previously searched room. The use of chocks and tool marks therefore provide an initial visual indication to firefighters that the room should not be searched again. However, the as the temperature of the chocks and tool marks approach the temperature of their surroundings within the building, the chocks and tool marks may become less visible in the images generated by the thermal imaging camera. Thus, over time the effectiveness of the chocks and tool marks may decrease and fail to serve their intended purpose.